1. Technical Field
The present invention relates to a detection method and a detection apparatus.
2. Related Art
Of a particular interest is a layered semiconductor device in which a plurality of substrates with electronic circuits formed thereon are stacked on each other in order to provide increased mount density for the semiconductor device. To stack a plurality of substrates on each other, a substrate bonding apparatus may be used to align and bond the substrates (see, for example, Japanese Patent Application Publication No. 2009-231671).
To stack a plurality of substrates on each other, the substrates may be appropriately positioned by referring to the outlines of the respective substrates. In this case, the outlines are detected by means of a transmissive optical system. However, when such an optical system is used to detect the outline of a layered substrate having a plurality of substrates stacked on each other and, in particular, the upper substrate is smaller in outline than the lower substrate, it is difficult to detect an accurate outline of the upper substrate.